Read the end of a log file

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Goes well past the readOnly/idempotent annotations: discloses the 1 MiB tail cap, refusal of paths outside allowed directories, symlinks leading out, and non-regular or binary files, plus secret masking and a prompt-injection warning about the content being machine data. These are exactly the behavioral traits an agent needs and none are derivable from annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Dense and front-loaded with zero filler; each clause (tail scope, filter, size cap, refusals, masking, injection warning) carries distinct information. It is a long single sentence but not padded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema present, the description needn't explain return shape, and it covers the safety, scope, and trust caveats around the read. Nothing an agent needs in order to invoke it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so path, lines, and contains are fully documented in the schema. The description only restates the contains filter at a high level and adds no format or default detail beyond the schema; baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (read/return last lines) and resource (text file in allowed log directories), plus the optional filter and the size cap. It names list_logs as the directory-discovery companion and is clearly distinguishable from journal_tail by operating on arbitrary files under allowed directories.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Points the agent to list_logs to find valid paths and states the scope constraints (allowed directories only, tail only, at most 1 MiB). It does not explicitly say when to prefer journal_tail or how this differs from it, so the when-not case is left implicit.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.